The reliability of semiconductor devices can be decreased by alignment errors that may occur during fabrication of upper and lower device structures on a semiconductor substrate. Moreover, the effect of such alignment errors on the reliability and/or other characteristics of semiconductor devices may increase as device feature sizes are decreased.
One approach to reducing alignment errors is to have a human operator visually observe and adjust the relative alignment of device structures during their fabrication processes. However, such human visual inspection may increase the elapsed time for the device fabrication process and may be prone to error. Furthermore, the visual inspection needs to be carried out before an opaque layer is formed on the upper and lower structures that are to be inspected.